1. Field of the Invention
The present invention relates to a method and an apparatus for realizing broadcast communication and data communication in a cellular network, and in particular to a cellular network system incorporating a data communication network and a video broadcast network, as well as the method and the apparatus thereof.
2. Description of the Prior Art
Existing mobile communication networks have been employing cellular architectures. Such cellular architectures generally support only voice and data unicast services. With the rise in demand for mobile audio and video, mobile video broadcast services have increased in the market of mobile communication. Especially, as the wideband wireless technology has developed rapidly, more and more discussion is directed to how to incorporate conventional mobile communication networks, wireless Internet data networks and broadcast networks in the next generation of wireless networks.
FIG. 1 shows a schematic diagram of a network architecture supporting mobile video broadcast service. Currently, two methods are often adopted to support mobile video broadcast service and described as follows.
The first method comprises employing an individual broadcast network, such as a DVB-H or DMB system, to support mobile video broadcast service. In this method, developed video content is stored in a content server by a content provider in the DVB-H or DMB system, then distributed to broadcast stations at respective locations via Internet (or a dedicated network) or a satellite system, and finally broadcast to terminals such as mobile phone, PDA, notebook computer or even in-vehicle TV, via the transmitting towers of the broadcast stations. These systems are generally independent of existing cellular networks, incapable of supporting mobile communication and need the establishment of a corresponding cellular network in the case of mobile communication. As a result, it requires two types of independent networks to perform mobile communication and video broadcast simultaneously, thereby resulting in a high cost.
The second method is to send video service as data of the same type as that of communication data by using the method of streaming media in the existing cellular networks, for example, GPRS, CDMA, or the like, so as to provide video broadcast service in cellular networks. In this case, the video content is first stored in a content server by a content provider and then broadcast to terminals over the cellular networks in the manner of streaming media. With the second method, however, since the conventional cellular networks are not designed for video broadcast, compared with the first method, each cell has to send multiple copies individually upon the transmission of the same content in order to support broadcast service. This results in inefficient use of the frequency spectrum.
In addition, most existing cellular networks are sectorized to reduce interference and expand capacity. When sectorized, each sector usually uses partial frequency spectrum, and it is thus more difficult to carry out video broadcast using the current sector-based cellular networks.